DAP Root Booster
Di-Ammonium Phosphate (DAP) is the world's most widely used phosphate fertiliser. Provides high phosphorus for rapid root development and strong early crop establishment, paired with nitrogen for initial leaf growth. Applied at planting for maximum benefit.
How to Use
Apply at Planting Only
DAP is a basal fertiliser — apply it in the planting hole or furrow at planting time. It is not effective as a top-dress because phosphorus moves very slowly through soil and must be placed in the root zone at the start of growth.
Measure the Correct Dose
Apply 100–150 kg/ha for most crops. For maize at 75 cm × 25 cm spacing, this equals approximately 2 g (one small pinch) per planting hole. Use a measuring scoop for accuracy — over-application of DAP near seeds causes germination damage.
Place Beside the Seed
Place DAP granules 5 cm beside and slightly below the seed level, never in direct contact. The 18% nitrogen in DAP converts to ammonia which is toxic to germinating seeds. A thin soil layer between the granule and seed is essential.
Cover and Plant
Cover the DAP granules with a thin layer of soil, then place the seed on top and cover. This layering technique ensures the seed germinates in nutrient-rich soil without direct fertiliser contact.
Follow with Nitrogen Top-Dress
DAP's nitrogen (18%) is sufficient for the first 2–3 weeks only. At 4–5 weeks after emergence, apply Urea or CAN as a top-dress for continued nitrogen supply through vegetative growth.
Check Soil pH Before Use
DAP temporarily raises soil pH around the granule as it dissolves — in alkaline soils (pH > 7.5) this can reduce phosphorus availability. Use a Soil pH Meter before application. On acidic soils (pH < 5.5), apply lime 6 weeks before using DAP for best P efficiency.
Key Features
Highest Phosphate Content
46% P₂O₅ is one of the highest phosphorus concentrations in any granular fertiliser — maximum root stimulus per kilogram applied.
Dual Nutrient Supply
The 18% N component kick-starts leaf growth while phosphorus drives root expansion — both critical in the first 3 weeks after germination.
Long Residual Effect
Phosphorus bonds to soil particles and remains available for several seasons. A single well-applied DAP dose can improve soil P levels for 2–3 crop cycles.
Critical for Tanzanian Soils
Most Tanzanian soils are phosphorus-deficient. DAP addresses the most common limiting nutrient that prevents crops from responding to nitrogen fertilisation.
Improved Drought Tolerance
A deep, extensive root system established by early phosphorus availability helps plants access deeper soil moisture during dry spells — critical resilience in rain-fed systems.
Better Flowering & Grain Fill
Phosphorus is essential for energy transfer (ATP) in the plant — crops with adequate P flower earlier, more uniformly, and convert photosynthate to grain more efficiently.
Application Tips
- On very acidic soils (pH below 5.5), phosphorus from DAP is quickly fixed into insoluble iron and aluminium compounds. Apply lime first, wait 6 weeks, then apply DAP for maximum phosphorus availability.
- DAP is a good alternative to NPK 20-10-10 for soils that are already nitrogen-rich from previous legume crops — the high P and lower N ratio matches the soil's actual needs.
- Mix with organic compost in the planting hole to improve P uptake — mycorrhizal fungi (stimulated by compost) dramatically increase phosphorus absorption from DAP applications.
- Store DAP away from lime and ammonium nitrate — contact with lime releases ammonia gas and contact with nitrate fertilisers creates a fire hazard.
